The embodiments disclosed herein relate to electrical components, and to a method of making such components.
Automated testing of integrated circuit components as well as other active and passive circuit members including circuit boards is often conducted using a contact probe to temporarily connect the device under test (DUT) to a test instrument. A signal is communicated by the contact probe through a suitable interconnection, which may include electric cables, hook up wires, connectors, and the like to the instrument which can process and/or display details of interest relating to the signal(s) of interest. The instrument may be any applicable test instrument which may include a voltmeter, an ammeter, an ohm meter, a multimeter, an oscilloscope, and the like. The signal of interest stemming from the DUT may originate from operation of the device under actual use conditions, under simulation or stress conditions, or under a burn-in test protocol. Alternately, the instrument or related circuitry may provide a reference signal or power to the DUT while simultaneously extracting a sample return signal for characterization or display. Often, more than one probe is used to simultaneously monitor more than one signal and/or more than one location. The number of probes can be in the range of 10 to 100 or more. In this case, individual probes may be arranged into an array of probes, which may be known by such terms as a bed-of-nails.
Characteristic of the probes in widespread contemporary use are probe elements having contact tips that are made primarily of metal. The disadvantage of using metal-tipped probes is that under certain conditions the typical metal-to-metal contact between the probe and circuit member potentially can introduce an undesired electric bias or even a surge into the measurement, particularly in AC measurements owing to a capacitance and/or inductance the metal tip induces into the test circuit. In this case, inaccurate results are produced. Other disadvantages to the use of metal tip probes include mechanical damage to the probe or to the circuit member such as scratching, denting, piercing, and even welding under high current conditions, contamination of the DUT due to transfer of metal surface oxides, and the like. A further disadvantage to metal probes used in large arrays is that they are generally heavy and require costly support structures to maintain positional precision.
Electric probes are also used in the medical industry and in the medical research field as temporary contacts to a wide range of materials and surfaces. These include such materials as human or animal skin, internal organs of the same, cells and groupings of cells, and the like. Often these probes are made from non-metal conductive materials such as inorganic salts in a suitable adhesive or gel medium which can adhesively join to and thereby serve to interconnect the surface of interest to a test instrument, such as an electrocardiogram monitor, a skin conductivity tester, and the like. The disadvantage to these non-metallic probes is that an adverse chemical reaction or allergic reaction may occur between the test subject and the contacting probe.
Certain electrical components used in electrostatographic printing machines are manufactured from composites, including composite plastics, that contain at least one filler which can be in the form of fine particles or fibers. The composites may be formed from a non-metallic pultruded composite member having multiple, generally circular cross section carbon fibers in a polymer matrix.
Various documents describe polymer composites containing carbon particles. U.S. Pat. No. 6,426,134 discloses single wall carbon nanotube-polymer compositions. U.S. Pat. No. 5,643,990 describes a variety of resins containing carbon fibrils.
It is known to use conductive nanoparticles in coatings. U.S. Published Patent Application No. 2008/0195187 describes a medical electrical lead having a conductor assembly covered by an insulating layer, and a shield covering formed from a polymer-matrix composite containing one or more nanosized metal structures, U.S. Published Patent Application No. 2003/0158323 describes an electrically conductive, optically transparent polymer/carbon nanotube composite. The composite is formed by dispersing the nanoparticles in an organic solvent and subsequent addition of one or more monomers. Alternately, the sequence may be reversed such that the monomer or polymer is dispersed in a solvent or diluent and the nanoparticles are subsequently added and dispersed therein.
It would be useful to develop new compositions, electrical components and processes for making compositions and electrical components that are useful in ultra-high frequency digital sensing and probing applications.